Template replication for full wafer imprint lithography

Typically, the Step and Flash Imprint Lithography (S-FILTM) process uses field-to-field drop dispensing of UV-curable liquids for step-and-repeat patterning. Several applications, including patterned magnetic media, photonic crystals, and wire grid polarizers, are better served by a process that allows high-throughput, full-wafer patterning of sub-100 nm structures with modest alignment. Full-wafer imprinting requires a full-wafer template; however, creation of a wafer-scale imprint template with sub-100 nm structures is not feasible with direct-writing approaches. This paper describes a practical methodology for creating wafer-scale templates suitable for full-wafer imprinting of sub-100 nm structures.The wafer-scale template is replicated from a smaller area master template using the S-FIL step-and-repeat process. The pattern is repeated to accommodate the wafer substrate targeted for a particular application. The tone of the master template is maintained by employing an SFIL/RTM (reverse tone) pattern transfer process. To create the replicate template, the patterns are imprinted onto a fused silica wafer that has been coated with chromium and an organic transfer layer. A silicon-containing resist, SilspinTM, is spun on to planarize the organic monomer material. Following an etch back of the Silspin, the monomer and transfer layer are patterned using the Silspin as a hard mask. The Silspin and monomer stack then serves as a masking layer for the chromium and fused silica etches. The remaining monomer and chromium are then removed to create a conformal replicate template.